The Stirlings are rated 91dB, so it’s an 8dB discrepancy on paper! I do appreciate that the Tannoy sensitivity specs indeed seem legit. I've noticed and enjoyed the greater efficiency when moving up in the line (91 to 93 to 96).
I tilt my Canterbury up a bit, and use a good amount of toe-in. It works for me, and sounds great. The image height is perfect. Stands tall enough to do the same job would mess with the aesthetic, and possibly introduce more resonance issues if they’re not extremely well made (heavy!).
I use HRS Nimbus spacers - basically solid aluminum hockey pucks with a small lip on top & bottom to accept the couplers - of differing height to create the tilt. The stock Canterbury GR spike feet & cups fit right in there.
I don’t see how a coaxial driver with symmetric dispersion and phase coherence (at the crossover point) is going to care at all whether tilted up or down or straight ahead. The bass response may be affected with tilt vs. stands, as it changes the bass driver’s coupling and proximity to the floor, but I don’t see why stands would necessarily be an improvement here either. I love the bass I get now.
Random thought: maybe those who love the stands have inadequate isolation for their components, and benefit from the decoupling effect of pedestal stands?